This project will be devoted to defining the mechanism by which Mycoplasma pneumoniae induces Primary Atypical Pneumonia. Model systems will include hamster tracheal organ cultures and human lung fibroblast cell cultures, both of which display a cytotoxic response to M. pneumoniae infection. Attention will be devoted primarily to two key aspects: Pathogen Attachment, and Nucleic Acid Metabolism. Glycoproteins will be isolated by techniques which involve pronase hydrolysis and selective solubilization in lithium diiodosalicylate. Extracted sialoproteins will be analyzed by flat-bed polyacrylamide gel electrophoresis, and the mycoplasma-binding protein (i.e., the M. pneumoniae receptor site) will be isolated with selective membrane filtration and/or chromatographic techniques. This receptor will be characterized relative to molecular weight, carbohydrate content, amino acid composition, and rates of synthesis and binding. The role of nucleic acid metabolism in this infection process will also be evaluated. The modification and transfer of epithelial cell adenine and related compounds will be studied as they are taken up by the infecting mycoplasmas. The chemical form of the radioactive adenine, and its ultimate fate in the pathogen, will be studied with thin-layer chromatography. These studies will directly contribute to our knowledge of pathogenic mycoplasmas, and will further our understanding of the host-parasite interactions which occur in respiratory disease.